McDonald's launched the advertising campaign built around “I'm Lovin' It” in 2003.
The campaign began internationally in Munich, Germany, and was developed with the advertising agency Heye & Partner. It was designed as a global platform that could be adapted for different countries while preserving the same short phrase and musical identity. McDonald's subsequently used the line across television, print, packaging, and digital marketing.
The campaign is notable because McDonald's had used many different slogans before it. “I'm Lovin' It” was intended to sound conversational and upbeat rather than describe a specific product or restaurant feature. Its compact wording made it easy to translate, localize, and attach to different advertisements.
The phrase is sometimes dated to 2004 because its worldwide rollout continued after the initial launch. The campaign itself began in 2003, making that the key historical date for the branding change.